DE2713508A1 - Low-pilling polyester fibres - contain co-condensed di:phenyl-silane-di:ol and polycondensate or di:methyl terephthalate! with bis:hydroxymethyl-cyclohexane - Google Patents

Abstract

Low-pilling polyester staple fibres contain predominant quantities, pref. >=90 wt. %, of poly-1,4-bis-(hydroxymethyl)-cyclohexane-terephthalate units pref. having structural formula: and 0.008-1.6 wt.%, w.r.t. dimethyl terephthalate used, of diphenylsilanediol, (I), or its hydrolysates. The staple fibres can be used in the mfr. of clothing, e.g. trousers, dresses, etc. Addn. of (I) modifies fibres so that, on wearing, pills fall off, due to the presence of a weak SiO- bond in the polymer chain. Addn. of (I) modifies fibres so that, on wearing, pills fall off, due to the presence of a weak SiO- bond in the polymer chain. Addn. of (I) can reduce fibre pilling from note (1), i.e. very strong, to note 5, i.e. no pilling, according to ASTM test standard D 1375-64. Extrusion properties and dyeability of polyester are unimpaired.

Description

Low-pilling polyester fibers

The invention relates to textile fibers made from high molecular weight linear fibers Polyesters with a reduced tendency to pilling.

The best known and technically most important representative of polyesters, which are used to manufacture textile fibers is polyethylene terephthalate or the polyester made from terephthalic acid and 1,4-bis (hydroxymethyl) cyclohexane. They are obtained by polycondensation of terephthalic acid or its derivatives with Glycol or 1,4-bis (hydroxymethyl) cyclohexane. The resulting after the melt spinning process threads produced are usually bundled in hot water and / or a Steam channel stretched, fixed in hot air, curled and cut. The on Fibers made in this way normally have a strength of 2.5 to 4.5 cN / dtex, an elongation of 20 to 50% and a boiling shrinkage of 0 to 3%.

These fibers can be used to produce textiles with, for example, excellent wear properties, such as low susceptibility to creasing, low water absorption and therefore easy drying or produce high strength and good abrasion resistance.

The high strength and good abrasion resistance of polyester fibers produced textiles have the disadvantage that e.g. items of clothing, like suits or sweaters, reinforced to show pills what their usability significantly restricts.

Pills or pills are the formation of small nodules or pills on the surface of the garment.

They arise from the fiber ends protruding from the surface or loose fiber parts tangle and not because of the good strength of the fiber fall off, but stick to the surface. A mechanical removal of the Nodules, such as brushing off or cutting off, are very complex and expensive and also have little success because new pills are constantly forming.

There is therefore a need to modify the fibers in such a way that that the pills fall off by themselves when wearing the garment.

Many attempts have been made to this end. One has e.g. tries to improve the strength and abrasion resistance of the polyester staple fibers reduce the fact that polyester has been spun and further processed, its molecular weight was lower than that of the commonly used polyesters. It resulted however, there are other disadvantages such as low melt viscosity Difficulty spinning (reduced performance in single-screw extruders), which is also expressed in large titre fluctuations. It also increases the abrasion resistance so greatly reduced that the dyed textiles were subject to greater stress Make white, milky surfaces visible. They arise because of the larger ones Brittleness the fibers become roughened when rubbing. The resulting abrasion and the increased scattered light make these areas appear brighter.

In addition, staple fibers made from polyesters with reduced When dyeing with carriers, dye molecular weight less well than staple fibers made of polyesters with normal molecular weight, so that the miscibility of these two Fiber types is limited.

It has now been found that staple fibers can be made from the polyester Terephthalic acid and 1,4-bis (hydroxymethyl) cyclohexane with the usual properties in terms of strength, elongation and boiling shrinkage, but greatly reduced tendency is obtained for pills if, in the production of the polyester, 0.01 to 2.00% by weight, preferably 0.30 to 0.90% by weight diphenylsilanediol, based on dimethyl terephthalate, adds and the thread-forming polymer has a relative viscosity before spinning from 1.60 to 2.00, preferably 1.65 to 1.93. As a relative viscosity In the context of this application, the ratio of the viscosity of a 1 iqen solution of the polyester from terephthalic acid and 1,4-bis (hydroxymethyl) cyclohexane in 60 Parts of phenol and 40 parts of tetrachloroethane to the viscosity of the pure solvent mixture, measured in equal units at 250C, understood.

The invention relates to fibers composed predominantly of poly-1,4-bis (hydroxymethyl) cyclohexane terephalate units containing high molecular weight polyesters containing 0.008 to 1.60 wt .-% cocondensed Diphenylsilanediol, based on the dimethyl terephthalate used or its hydrolysis Products.

These fibers are obtained by using the high molecular weight described above Spun polyester, appropriately drawn and a hydrolysis treatment subject.

The hydrolysis can advantageously be designed so that one it is combined with stretching under hydrothermal conditions by the spun material in the water bath at temperatures of 50 to 98 ° C, preferably from 80 to 950C, and / or in a steam channel at temperatures of 120-1650C, preferably 130 to 1600C, stretched and puckered in a known manner and cut into stacks.

It was found to be a significant advantage that the extruder performance when Spinning despite the slightly lower molecular weight than unmodified Polyesters made from terephthalic acid and 1,4-bis (hydroxymethyl) cyclohexane are no less and the polyester can be dyed just as deeply when dyeing with carriers like normal material.

Another advantage of this process is that you can use the polyester can also spin as granules and not necessarily spin continuously got to. Another advantage has been found to be that the addition of diphenylsilanediol the rate of polycondensation increases, i.e. the required molecular weight can be reached in less time.

The polyester suitable for spinning is obtained by adding 0.01 to 2.00% by weight, preferably 0.30 to 0.90% by weight, of diphenylsilanediol, based on dimethyl terephthalate, to the reaction mixture before the transesterification, with It has been shown that about 80% of the diphenylsilanediol is subsequently contained in the finished polyester, it being assumed that it is largely chemically bonded as a chain segment with the formula is present in the polyester. The Si-O bond is a weak point in the polymer chain because it is broken in the presence of water. It has been found that in the present case the bond is susceptible to hydrolysis, but in contrast to other known processes it is possible, without any noticeable hydrolytic degradation, to spin the polymer formed after the polycondensation from an autoclave in water in coarse titers and to granulate it .

The relative viscosity of the granules obtained in this way is exactly the same the relative viscosity of a melt block spun in air.

Only with the hydrothermal treatment, which is advantageous with the drawing of the fine denier threads 0 in a water bath in the temperature range of 50 to 980 cm, preferably from 80 to 950 ° C., and / or in a steam channel at temperatures from 120 to 1650 ° C., preferably 130 to 160 ° C., becomes part of the Si-O bonds are hydrolytically split and a certain degree of molecular degradation occurs a. The relative viscosity of the staple fibers treated in this way is normally 0.15 to 0.20 units lower depending on the diphenylsilanediol content, if the filaments have a relative viscosity of 1.60 to 2.00 prior to drawing. Thus, the relative viscosity after stretching is 1.45 to 1.85.

It has been found that an addition lower than 0.01% by weight is sufficient Diphenylsilanediol does not lead to pill-resistant staple fibers because then the molecular Degradation is too low.

A greater addition of diphenylsilanediol than 2.00 E by weight causes difficulties during polycondensation, because molecular weights that are too low are achieved. aside from that the molecular degradation in the stretching bath is so strong that from the in this way produced Staple fibers cannot be used to produce a usable item of clothing.

The polyesters based on terephthalic acid and 1,4-bis (hydroxymethyl) cyclohexane can also be modified, but at least 90% of them should consist of recurring parts of the formula exist. In addition to terephthalic acid, these copolyesters can also contain isophthalic acid, hexahydroterephthalic acid and also minor amounts of aliphatic dicarboxylic acids, such as sebacic or adipic acid. In addition to 1,4-bis (hydroxymethyl) cyclchexane, ethylene glycol or 1,4-butanediol, for example, are also suitable as glycol components.

The reduced tendency to pill can be seen in the laboratory test after ASTM test standard D 1375-64 (Tests for Pilling Resistance of Textile Fabrics-Part F-Random Tumble Pilling Tester). The staple fibers to be examined were used for the test twisted and processed into flat knitted fabrics. The individual samples are graded on the following scale, grade 5, excellent resistance (no pilling) grade 4 good resistance (light pilling) Grade 3 medium resistance (medium pilling) Grade 2 low resistance (strong Pilling) grade 1 very low resistance (very strong pilling) staple fibers, made from a polyester having a content of 0.008 to 1.60% by weight, preferably Has 0.24 to 0.72 wt .-% diphenylsilanediol and a relative viscosity of 1.60 to 2.00, preferably 1.65 to 1.93, show the pill grade 4 to 5, while staple fibers made from pure polyester made from terephthalic acid and 1,4-bis (hydroxymethyl) cyclohexane with a relative viscosity of e.g. 1.75 have a pill rating of 1 to 2.

It was extremely surprising that the polyester granules described above with an addition of 0.01 to 2.00% by weight, preferably 0.30 to 0.90% by weight, of diphenylsilanediol and a relative viscosity of 1.60 to 2.00, preferably 1.65 to 1.93, none Caused lower performance of the extruder compared to the unmodified polyester. This is because the melt viscosity of the modified with diphenylsilanediol Polyester with the same relative viscosity as a homopolymer by approx. 100 % higher (measurement of the melt viscosity according to the plate-cone method, device Rotovisko from

Haake Brothers, Berlin; Temperature 3000C, without nitrogen flow, heating-up time 3 minutes).

For example, the following was measured: rel. Melt Viscosity Viscosity at 300 C unmodified 1.75 380 poise polyester polyester + 0.80% by weight 1.75 750 poise Diphenylsilanediol The relative viscosity given in the examples was measured as indicated on page 3.

Example 1 Before the reaction of dimethyl terephthalate with 1,4-bis (hydroxymethyl) -cyclohexane are the reaction mixture 0.75 wt .-% diphenylsilanediol, based on Dimethyl terephthalate, added. The transesterification takes place within one hour, the temperature being increased from 200 to 2600C at a pressure of 8 bar. Then 0 there is a temperature increase of 305 C within 30 minutes. This temperature is retained for the polycondensation, the pressure being reduced to approx. 1 Torr will. The polycondensation is over after 1.2 hours. Then from the autoclave spun in water to form a coarse monofilament and granulated.

The granules produced in this way show a relative viscosity of 1.74, corresponding to a melt viscosity at 3000C of 730 poise.

The granulate is melt-spun through a Multi-hole nozzle spun into threads with a single titer of 10 dtex and with a Wound at a speed of 1100 m / min. The filaments become a cable of 100,000 dtex, in hot water at 900C and then in a steam channel stretched at 1300C in a total ratio of 1: 3.00, crimped in a stuffer box, dried in hot air and then cut into staple fibers 60 mm in length.

The fibers show a strength of 3.3 cN / dtex, an elongation of 35% and a boiling shrinkage of 1%. The titer is 3.3 dtex and the relative Viscosity is 1.56.

Yarns with a left twist were made from the staple fibers of 495 turns / m and a right turn of 310 turns / m and the were then processed into a Flachqestrick. This knit was the Laboratory pill test according to ASTM test standard D 1375-64 and achieved after 110 Minutes test duration the excellent pill grade 5, i.e. no pilling.

If you compare the staple fiber just described with a staple fiber, those from the unmodified polyester from terephthalic acid and 1,4-bis (hydroxymethyl) -cyclohexane of the same relative viscosity of 1.74 was produced and the The staple fiber described above is completely identical in terms of textile properties, the knitted fabric made of these staple fibers shows in the laboratory pill test after 110 minutes Test duration to grade 2, i.e. heavy pilling.

From the staple fibers, made from a polyester with an additive of 0.75% by weight diphenylsilanediol and the staple fibers with the same relative Viscosity, but from the unmodified polyester, fabrics were made and these processed into pants. The pants showed after a wear test of 250 hours a completely different picture. The trousers made of staple fibers with the addition of diphenylsilanediol shows no pills or only very few pills in a few places while the pants are off the unmodified polyester without the addition of diphenylsilanediol a very troublesome Pills showed. The day trial thus confirms the one already obtained in the laboratory test Finding.

Example 2 Before the reaction of dimethyl terephthalate with 1,4-bis (hydroxymethyl) cyclohexane add 0.65% by weight of diphenylsilanediol to the reaction mixture, based on dimethyl terephthalate, added. The transesterification takes place in an autoclave, the temperature during 1 hour from 2000C to 2600C. The pressure is left at 8 bar. Then the temperature rises to 305 ° C. over 30 minutes for polycondensation at 305 C the pressure is reduced to 1 torr. It ends after 1 hour, like that that is then spun in water and granulated.

The granulate has a relative viscosity of 1.74 and a melt viscosity of 0 of 750 poise at 300 C.

The granulate is melt-spun through a Multi-hole nozzle spun into threads with a single titer of 10 dtex and with a Wound at a speed of 1100 m / min. The filaments become a cable of 100,000 dtex, in hot water of 900C and 0 then in one Steam channel stretched at 130 C in a total ratio of 1: 3.00, in a stuffer box crimp crimped, dried without tension in hot air and then into staple fibers cut to a length of 60 mm.

The fibers have a titer of 3.3 dtex and a strength of 3.1 cN / dtex, an elongation of 37%, a boiling shrinkage of 0% and a relative viscosity from 1.59.

Yarns with a left twist were made from the staple fibers of 495 turns / m and a right turn of 310 turns / m and the were then processed into a flat knitted fabric. This knit was the Laboratory pill test according to the above-mentioned ASTM test D 1375-64 and achieved After a test duration of 120 minutes, the excellent pill grade 5, i.e. no pilling. Compares the staple fiber just described with a fiber made from the copolyester with the same addition of 0.65% by weight diphenylsilanediol, but a relative viscosity of the granulate of 2.10 was produced, this shows a slightly higher strength and otherwise the same textile properties in the laboratory pill test according to the ASTM test standard D 1375-64 Pill grade 2 after 120 minutes of testing, i.e. heavy pilling.

On the other hand, it was used to make a staple fiber from a polyester with the same diphenylsilanediol content, but a relative viscosity of 1.50 proceeded, so a strong molecular degradation occurred during the stretching that that no serviceable garment could be made from the fibers.

Claims (6)

Claims 1. Fibers made from predominant proportions of poly-1,4-bis (hydroxymethyl) cyclohexane terephthalate units containing high molecular weight polyesters containing 0.008 to 1.6 wt .-%, based on the used dimethyl terephthalate, cocondensed diphenylsilanediol or its hydrolysis products. 2. Fibers according to claim 1, characterized in that the polyester consists of at least 90 wt .-% of recurring structural units of the formula exist. 3. Fibers according to claim 1 or 2, characterized in that the Polyester has a relative solution viscosity of t eleven measured at 250C in a 1% strength Solution in a mixture of 60 parts of phenol and 40 parts of tetrachloroethane of 1.45 to 1.85. 4. Fibers made from predominantly poly-1,4-bis (hydroxymethyl) cyclohexane terephthalate units containing high molecular weight polyesters, characterized in that the polyester by transesterification of a reaction mixture consisting essentially of dimethyl terephthalate, 1,4-bis (hydroxymethyl) cyclohexane and 0.01 to 2 wt.% Diphenylsilanediol, based on on the amount of dimethyl terephthalate used, and subsequent polycondensation were obtained. 5. Process for the production of fibers from high molecular weight polyesters by spinning the melt of a predominant proportion of poly-1,4-bis (hydroxymethyl) cyclohexane terephthalate units containing high molecular weight polyester, stretching and subsequent processing the threads thus obtained into staple fibers, characterized in that a polyester spun containing 0.01 to 2.0 wt. t of diphenylsilanediol in cocondensed form and subjecting the obtained fibers to hydrolysis. 6. The method according to claim 5, characterized in that the high molecular weight Polyesters have a relative viscosity of 1.60 to 2.00.